1. Field of the Invention
This invention relates to a semiconductor laser device and a process of assembling the same, and more particularly to a semiconductor laser device having a lead extending through a lead mounting hole of and fixed to a stem by way of an insulator and also to a process of producing such semiconductor laser device.
2. Description of the Prior Art
A semiconductor laser device is already known and disclosed, for example, in Japanese Utility Model Laid-Open No. 61-85175 wherein a semiconductor laser element is assembled to a stem with a heat sink interposed therebetween and is sealed with a cap. In such semiconductor laser device, an electrode is led out for the external connection such that a lead is passed through a lead mounting hole formed in a stem and is fixed to the stem by way of glass and an inner end of the lead is connected to the electrode of the semiconductor laser device by way of a wire.
FIG. 6 shows a stem and a lead of such a semiconductor laser device. Referring to FIG. 6, a stem a has a supporting portion b formed in an integral relationship at a central portion of a surface thereof such that a semiconductor laser element not shown may be bonded to the support portion b. Three leads c are assembled to the stem a. In particular, one of the three leads c is fixed directly to a rear face of the stem a by means of welding while the other two leads c extend through lead mounting holes e of the stem a and is fixed to the stem a in an electrically isolated condition from the stem a by way of glass d filled between the leads c and the stem a in the lead mounting holes e.
Such two leads c are assembled to the stem a in such a manner as illustrated in FIGS. 7A and 7B. First, a pair of leads c each having an anodic oxidized surface and a pair of glass rings d each produced by molding special glass powder having a low melting point into a ring are prepared as seen in FIG. 7A. The anodic oxidation of the leads c facilitates fixation thereof to the glass rings d by melting of the glass rings d by heat.
Subsequently, the glass rings d are inserted into the lead mounting holes e of a stem a, and then the leads c are inserted into the glass rings d. Then, the stem a, glass rings d and leads c are placed in this condition into a furnace in which they are baked at a temperature of, for example, 420.degree. to 430.degree. C. to cause the glass rings d to melt in order to fusion mount the leads c onto the stem a as seen in FIG. 7B.
After the stem a to which the leads c are assembled is removed from the furnace, anodic oxidation films on surfaces of the leads c are removed and then the surfaces of the leads c are plated with a suitable metal. Anodic oxidation films must be removed because they are an insulator and will obstruct assurance of an electric conductivity of the leads c.
By the way, such a process of assembling a semiconductor laser device as illustrated in FIGS. 7A and 7B, that is, the assembling process of a semiconductor laser device wherein the leads c are passed into the lead mounting holes e of and fixed to the stem a by way of the glass d, is disadvantageous in that it has a comparatively great number of assembling steps and it is difficult to reduce the production cost of a semiconductor laser device. This is because the steps of anodic oxidizing leads c after shaping, fusion mounting the leads c onto the stem a by way of the glass rings d, removing anodic oxidation films on surfaces of the leads c and plating the surfaces of the leads c are required only for the assembly of such leads.
Besides, since the glass rings d require a very high material cost and besides likely get out of shape, operations of inserting the leads c into the glass rings d and then inserting the glass rings d into the lead mounting holes e of the stem a are difficult to carry out. Further, when the stem a is placed into a furnace in order to bake the glass, it is necessary to hold the stem a, glass rings d and leads c in a predetermined fixed positional relationship, and to this end, an expensive special carbon jig is required. Those facts make a factor of raising the cost of a semiconductor laser device and obstructing reduction in production cost of a semiconductor laser device.